Story highlights

Source tells CNN that authorities think one person went through hole in plane and fell to death

The explosion rocked Daallo Airlines Flight 3159 soon after it took off from Mogadishu

Initial tests of the damage are positive for explosive residue, a knowledgeable source says

Nairobi, Kenya (CNN)An explosion rocked a commercial plane after it set off above East Africa on Tuesday, injuring two people before the pilot landed safely, a passenger said.

Somali authorities later discovered a body near Mogadishu they believe fell from the Daallo Airlines plane.

Late Tuesday night, a source with knowledge of the investigation told CNN that Somali authorities confirmed one passenger had been blown or ejected out of the hole created by the explosion. Somalia's National News Agency reported that one passenger died after falling from the plane.

Pictures from the ground showed a hole in one side of the airliner, just above its wing and slightly smaller than one of its doors.

Initial tests of the damage on Flight D3159 came back positive for explosive residue, a source with knowledge of the investigation told CNN.

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A spokesman for Somali Prime Minister Omar Abdirashid Ali Sharmarke didn't immediately indicate a bomb had gone off mid-flight, echoing a Daallo Airlines worker in saying "the incident is under investigation."

Oxygen masks dangle from the plane's ceiling after Tuesday's explosion.

"There is a lot of conflicting information," said the Prime Minister's spokesman, Abdisalam Aato.

Daallo CEO Mohammed Ibrahim Yassin told Forbes.com that it was too early to say what caused the explosion.

"Nothing is certain," he said. He acknowledged that some people believed there was a bomb. "The Civil Aviation (Authority) thinks differently."

An airport official estimated the Daallo plane was between 12,000 and 14,000 feet high when the blast occurred not long after it took off from Mogadishu International Airport.

The pilot then flew the Airbus A321-111, which had originated in Jeddah on Saudi Arabia's Red Sea coast, back to the Somali capital.